Hard facing alloys



United rates Patent C No Drawing. Filed June 7, 1961, Ser. No. 115,314 1Claim. (Cl. 75128) This invention relates generally to hard facingalloys and to hard castings, but has reference more particularly toimprovements in the alloys described in my US. Patent No. 2,801,164.

In the aforesaid which consists of to about 4.5

patent, an iron base alloy is described carbon in amounts of from about1 chromium in amounts of from about 17% to about 27%, molybdenum inamounts of from about 4% to about 10%, cobalt in amounts of from about5% to about 25%, and silicon in amounts up to about 4%, the remainder ofthe alloy being substantially all iron, and the alloy beingsubstantially free of tungsten.

Although the aforesaid alloy has an exceptionally high hardness for thecarbon-chromium range which it includes, the carbides in the alloy areof needle-like or needleshaped form. Where the carbides are of this formor shape, there is a tendency for the carbides to grow or merge intoeach other, thus producing a continuous relatively brittle structure.

I have discovered that by incorporating relatively small amounts ofnickel in the alloy, in the range of from about 1% to about 2% nickel,and preferably about 1.5%, the carbides in the alloy, instead of beingof needle-like form or shape, assume the form of euhedral or well-shapedcarbides. Where the carbides are in euhedral or Wellshaped form, thecarbides are discrete, and there are present in the structure of thealloy no continuous lines or planes of brittleness, so that the alloyresists wear to a greater extent. These advantages become more apparentas the carbon content of the alloy increases.

The alloy, owing to this difference in the carbide structure, is able toWithstand more severe impact than the material with the needle-likecarbide structure.

In accordance with the invention, the alloys fall Within the followingranges:

It is to be understood that the expression the remainder beingsubstantially all iron, as used in the claim, is to be construed asincluding any other ingredients or impurities in relatively small ortrace amounts, Which are found associated With the various constituentsof the alloy, as for example, manganese, sulphur and phosphorus.

Having thus described my invention, I claim:

An iron-base alloy consisting of carbon in amounts of from about 1 toabout 4.5%, chromium in amounts of from about 17% to about 27%,molybdenum in amounts of from about 4% to about 10%, cobalt in amountsof from about 5% to about 25%, nickel in amounts of from about 1% toabout 2%, and silicon in amounts up to about 4%, the remainder of thealloy being substantially all iron, said alloy characterized by the factthat the carbides in the alloy are of euhedral form.

No references cited.

